The invention relates to a method of winding a continuous material web, especially paper or board web, onto a spool to form a wound reel and to the transfer of the web to a successive spool and relates to a winder for the continuous winding of a material web, especially paper or board web, and particularly to the movement of a contact pressure drum and a new spool for transferring to the new spool and for winding the web.
A winder of the type addressed here in disclosed in EP 0 697 006 B1, and has a contact pressure drum that is rotatably arranged on a vertically displaceable lifting table. A continuously incoming material web, for example a paper web, is guided over a circumferential region of the contact pressure drum, also referred to as a supporting roll or carrier drum, and wound onto a spool to form a wound reel. During the entire winding process, the contact pressure drum, which is pressed against the circumference of the wound reel and forms a winding nip with the latter, is arranged underneath a horizontal guide path, along which the initially empty spool and, following the severing and transferring of the material web, said spool together with the wound reel wound thereon, is guided. In order to prepare a spool change, the contact pressure drum is moved vertically upward and at the same time the almost finished wound reel, which hitherto has been held in a fixed location in a winding position, is displaced along the guide path in the direction of a finished reel position. During this operation, the line contact between contact pressure drum and the almost finished wound reel is maintained. The contact pressure drum is pressed against the circumference of an empty spool, which is displaced along the guide path out of a waiting position into a winding start position, and forms a second winding nip with said empty spool. The material web is then severed, its free end is wound onto the empty spool and the finished wound reel is displaced horizontally in such a way that the contact between said wound reel and the contact pressure drum is broken. In order to transfer the new wound reel from the winding start position into the winding position, the contact pressure drum is displaced vertically downward and the new wound reel is displaced along the guide path. In the process, the new wound reel rolls over a circumferential region of the contact pressure drum, that is to say that the winding nip is maintained during the transferring of the new wound reel into the winding position, and travels over a circumferential region of the contact pressure drum. After the new wound reel has reached the winding position and is fixed in this position in a fixed location, the increasing wound-reel diameter is compensated for by a vertical downward movement of the contact pressure drum. This means that, during the entire winding process, the contact pressure drum is pressed from below against the circumference of the wound reel and must therefore carry part of the weight of the wound reel. Because of the sagging of the spool with the wound reel wound thereon, the line force in the winding nip is nonuniform over the web width, which reduces the quality of the finished product. Furthermore, fluctuations in the line force may occur while the new wound roll is being transferred from the winding start position into the winding position, that is to say is traveling over the circumferential region of the contact pressure drum. This may also lead to fluctuations in the line force and thus to discontinuities in the winding hardness or, respectively, the winding hardness profile, as a result of which the winding result is also influenced in an undesired way. Furthermore, it has been shown that, as a result of the vertical moving of the contact pressure drum in order to influence the line force, a complicated control system is necessary. Nevertheless, in many cases, the line force cannot be set sufficiently accurately or jumps and fluctuations in the line force, which are brought about for example by an imbalance in the wound reel, cannot be set sufficiently accurately.